Vinyl chloride polymerization in reactor coated with build-up suppressant product

Abstract

Polymerization of vinyl chloride in aqueous suspension using a polymerization reactor having adherently deposited on internal surfaces thereof a build-up suppressant coating comprising a product of build-up suppressant activity formable by (and preferably formed by) the condensation of an effective 1-naphthol (preferably 1-naphthol itself) and formaldehyde. The condensation is preferably effected in a base-catalyzed reaction; it may also (less preferably) be effected in an acid-catalyzed reaction. The coating product itself and a process for its production are also claimed.

We claim: 
     
       1. A process for the polymerisation of vinyl chloride in aqueous suspension wherein the polymerisation is carried out in a polymerisation reactor having adherently deposited on internal surfaces thereof a build-up suppressant coating comprising a product having build-up suppressant activity which is formed by the condensation of formaldehyde and an effective 1-naphthol of formula ##STR3## wherein n is 0 or 1; m is 0, 1, 2 or 3; and R 1  and R 2  which may be the same or different are selected from Cl, lower alkyl (1-5 carbon atoms), hydroxyl, and lower alkoxyl (1-5 carbon atoms). 
     
     
       2. A process according to claim 1 wherein in said effective 1-naphthol m is 0, 1 or 2. 
     
     
       3. A process according to claim 1 wherein the condensation is effected in a base-catalysed reaction. 
     
     
       4. A process according to claim 1 wherein the condensation is effected in an acid-catalysed reaction. 
     
     
       5. A process according to claim 1 wherein said an effective 1-naphthol is 1-naphthol itself. 
     
     
       6. A process according to claim 1 wherein said an effective 1-naphthol is selected from 1,3-dihydroxy-naphthalene, 1,5-dihydroxy-naphthalene, and 1,7-dihydroxy-naphthalene. 
     
     
       7. A process according to claim 1 wherein the coating is formed by the application to the reactor internal surfaces of an alkaline aqueous solution (where preparable) comprising the product having build-up suppressant activity. 
     
     
       8. A process according to claim 7 wherein said alkaline aqueous solution is the direct or diluted solution obtained from the condensation in a base-catalysed reaction. 
     
     
       9. A process according to claim 1 wherein the molar admixture ratio for the condensation of said an effective 1-naphthol/formaldehyde is within the range 1.1/1.0 to 1.0/1.2. 
     
     
       10. A process according to claim 9 wherein said molar admixture ratio is substantially 1.0/1.0.